12 PHYSIOLOGY OF THE INVERTEBRATA. 



way for the synthesis of this compound ; and in their re- 

 searches * on living and dead protoplasm, they have arrived 

 at the conclusion that living protoplasm contains an alde- 

 hydic group of elements. In their experiments on the living 

 protoplasm of the fresh-water algae, Spirogyra and Zygnema, 

 growing in spring- water containing O.I per cent, of dipotas- 

 sium phosphate and ammonium nitrate, Loew and Bokorny 

 found that the living cells had the power of reducing silver 

 from very dilute alkaline solutions of salts of that metal. 

 Dead cells do not give this reaction. 



Loew and Bokorny have experimented (with the same 

 result) upon the cotyledons of Heliantlius minits, the epidermal 

 hairs of plants, the sap of the pine and oak, the cells of fruits, 

 fungi, and also many of the Infusoria. They conclude 

 from these observations that living protoplasm contains an 

 aldehydic group of elements, whereas there is no such group 

 in dead protoplasm. 



Eeinke (JSerichte der JJeutschen Chamischoi Gesellschaft, vol. 

 14, p. 2144; vol. 15, p. 107) says that the aldehydic nature, 

 as tested by an alkaline silver solution, is only a property of 

 the protoplasm of the chlorophyll, for he failed to find it in 

 the protoplasm of cells in unopened buds ; therefore he thinks 

 it is probable that it is formed only in the presence of sunlight 

 by the chlorophyll corpuscles. 



Mori (Chemisches CentralUatt [3], vol. 13, p. 565) considers 

 that formic aldehyde is the first product of assimilation, for 

 he detected (by the action of a solution of silver nitrate) a 

 substance which reduced the nitrate in plants containing 

 chlorophyll which had been exposed to sunlight. When the 

 same plants were left for about forty-eight hours in a dark 

 place, so that on applying the test again the first products of 

 assimilation might be used up, no reduction of silver nitrate 



* Vie Ghemische Kraftquelle im hhenden Protoplasma; also Berichte der 

 Deutschen Ohemischen Gesellschaft, vol. 14, p. 2508; vol. 15, p. 695; 

 Pflilger^s Archio fur Physiologie, vol. 25, p. 150 ; vol. 45, p. igg ; and Bot. 

 t'entr. 1889, p. 39. 



